Velocity vs. accuracy: Does it REALLY matter? Part 3

The test rulesIn this test, I wanted to know only if there was anything to the claim that high velocity is an accuracy killer for an airgun. So, here’s how I proceeded. I would shoot ten 10-shot groups at a target 50 yards away. Five would be shot at an average speed of 900 f.p.s. or less and a very tight extreme velocity spread over a 10-shot string. That speed falls right into the range currently espoused by champion field target shooters (850-900 f.p.s.). Five more 10-shot groups were to be fired at an average speed well over 1,050 f.p.s., with an equally tight extreme spread. While the faster shots may not always break the sound barrier, which is variable, they’ll be well within the transonic region, where they should be disturbed in flight by their own shockwave.

The first pellet selected was a Chinese dome. Here’s how it performed.

To assure the port restrictor screw was operating consistently, I reinstalled it after shooting the high velocity string and got another low-velocity average of 871 f.p.s., with a maximum spread of 9 f.p.s. Folks, that’s not only good consistency for a spring gun–most regulated PCP rifles can’t do any better. Especially in light of the fact that I was NOT using sorted pellets! Every shot came straight from the factory tin. And after a roll across the lube pad, the pellet was inserted directly into the barrel.

One thing about using lubed pellets in a powerful spring gun–they can diesel. To keep dieseling to an absolute minimum, keep that lubricant as light as possible. The numbers you see in the tables above were achieved with lubed pellets, but I also shot other strings that went faster and had much larger total spreads. I knew those shots were dieseling. By taking pains to lube as lightly as possible, I was able to get very small velocity spreads and repeat velocity at will with the air restrictor in or out. I also learned how to apply the lube just right.

Shooting the gunI shot the rifle off a very stable bench with a double sandbag rest (forearm and buttstock both rested). I waited out the wind until the shot had the best chance of being on target. And I made sure I was into good shooting form before starting the strings.

One more thing–and this might be important to everybody. While reading about schuetzen shooting of the 19th century, I happened across the fact that the best shooters always oriented each bullet in the bore exactly the same way. They took note of where the mold line was and always aligned it the same in the breech or false muzzle of their gun.

A few years ago, I bought some super-accurate lead bullets from a schuetzen supply house, and they all had a small mark in the nose to help with this orientation. I had completely forgotten about that little fact; but sure enough, when I checked the pellets, I could see a seam on them as well. So for this first test, I used my bifocals to see and align every pellet in the same orientation at loading. The flip-up barrel of the Whiscombe made this possible; I’m not certain how effective it would be in a turnbolt gun like a Marauder or Crosman 2260.

I selected the Chinese domed pellet because it went fast enough at high velocity. Crosman Premier 10.5-grain pellets topped out at about 1,000 f.p.s., which was too close to the low edge for my liking. The Chinese domes were well into the transonic region, and I wanted to get as far into that realm as possible so that any outcome can be supported by a clear velocity distinction–both well above and below the expected accuracy “barrier.”

So, let’s get shooting and let the chips fall where they may!

The best laid plans…Boy, did those chips ever fall! They fell everywhere–except where they were supposed to! In short, I got skunked.

It was nothing less than I deserved for being so cocky about this test. My first “group” had opened to three inches before the seventh shot was fired! The gun was all over the paper. True, there was a steady 5 mph breeze from the left, but that was no reason for a group that big. My own overconfidence and lack of pretesting had led me right into the trap.

Having humiliated myself so completely, I decided to try a group at high velocity, as well. They were even worse than the slow ones. Inside four shots, I was looking at more than four inches of dispersion! Also, I believe they were actually breaking the sound barrier, because there was a pronounced crack with every shot. It could have been produced by a strong dieseling as well, but since the temperature was 42 deg. F that day, I think they may have gone supersonic. Needless to say, with these poor results, I did not proceed with the test.

On the way home, I wondered what sense could be made of this mess. I didn’t want to abandon the test, but reporting three-inch groups at 50 yards didn’t seem too desirable, either. Then I remembered another test I performed several months back where I learned that the Chinese domes are much more sensitive to wind than either Crosman Premier lites or heavies. Had I chosen the wrong pellets for the test?

Back to the rangeThe next day, I went back to the range. This time, I was armed with Crosman Premier 7.9-grain pellets as well as Chinese domes. Though initially overlooking them because I thought they were too light, I was now glad to have them available.

All this shooting took place at the end of March 2001–right at the start of spring in the Northern Hemisphere. Many blustery days had passed before I was able to get to the range to fire the first shot. Then my car compounded the problem by suddenly requiring a new transmission! I had been so confident in the planning of this test, but the actual execution quickly brought me back to reality.

The 7.9-grain Premiers came as a stroke of extreme good fortune, for they shoot even faster than the heavier Chinese domes, plus they have much stronger skirts to take the savage blast from the Whiscombe on high power.

The standard port restrictor Whiscombe sends with their guns delivered velocities in the 820s with light Crosman Premiers, so the hole did not need much enlarging. Luckily, I hit it right on the head the first time, with an average of 902. And look at that extreme spread again. Another very tight string.

With the port removed, the pellets were definitely supersonic, as the crack of each shot proclaimed on my basement range. Although the extreme spread opened up a bit, it is still very tight–too tight for all the shots to be diesels. I felt I could return to the range and try again.

The second time around

The best low-velocity group measured 1.718″ c-t-c at 50 yards with Crosman 7.9-grain pellets. All pellets were lightly lubricated. At this velocity (902 f.p.s. average), the pellet is at the upper limit for accuracy, according to the theory that says 900 f.p.s. is as fast as a pellet should go. This group measures just 76 percent as large as the high-velocity group below.

The best high-velocity group measured 2.254″ c-t-c at 50 yards. Pellet was a Crosman Premier 7.9-grain fired through the same barrel as the low-velocity group above. At supersonic speeds (1,140 f.p.s.), the pellet breaks the sound barrier with a loud crack but has probably slowed down to subsonic by the time it reaches the target 50 yards away.

The second day at the range had better weather than the first, but only because I arrived before 8 a.m., when the wind was at its calmest. There was a prevailing breeze of 1-5 mph from my left throughout the session. The temperature was a chilly 26 deg. F–but it was the best day I’d gotten so far, and the absolute last chance to get this test started.

Instead of sorting the pellets by weight, I used them straight from the box. That’s not the way I wanted to do it, but time was forcing such concessions. Since this was not a complete test, I’ll do it over, but I wanted to give some kind of preliminary results of my experience.

I took each pellet and rolled it on a lubed pad before loading. This time I paid no attention to the orientation of the pellet as it was loaded–another detail for the next go-round.

Premier lites loaded with more resistance than the Chinese domes. I attribute part of that to skirt size and part to Crosman’s harder lead alloy.

As before, I shot the slower pellets (902 f.p.s.) first, then switched to the higher speed (1,140 f.p.s.) pellets. Because the wind was picking up and I was freezing, I limited the number of groups to two for each velocity.

The first five shots at low velocity went into 1.4″, but the last five opened that up to 1.741″. The second group measured a slightly smaller 1.718″. That’s for 10 shots off a double-bag rest at 50 yards. The gun was leveled for each shot and, being a Whiscombe, it is completely recoilless.

I then removed the transfer port restrictor and shot the two high-speed groups. Each shot cracked like a .22 long rifle, breaking the sound barrier. The first group measured 2.503″, the second 2.254″.

The combined size of both low-speed groups measure almost 73% the combined size of both high-speed groups.

What does it mean?Four groups prove nothing. And even when I rerun the test and have 10 more groups to add, they still won’t be conclusive. But the expected correlation between velocity and group size does seem to have been upheld in what I’ve accomplished so far. The largest low-velocity group (1.741″) is still smaller than the smallest high-velocity group (2.254″)–more than a half-inch smaller, in fact.

You might think I let my expectations bias the outcome, but I tried hard not to. By using a double-bag rest (that’s a bag under the forearm and another bag under the buttstock), I’ve removed as much random gun movement as possible. The Whiscombe’s recoilless nature allows it to be rested, where most springs gun shouldn’t be. A higher-power scope might make for smaller groups, but that would seem to work for both velocities. Besides, it would be impossible to mount on this model Whiscombe.

Different pellets might give different ratios of group sizes in this test, but if the theory proves true, any diabolo travelling at subsonic velocities should be more accurate than the same pellet going supersonic.

This test should also be tried with a PCP rifle. At present, there are only a few that have the broad range of adjustability needed, but the Marauder, the Condor and the Air Force Talon should all be up to it.

One final note illustrates the value of 10-shot groups. When I shot the first low-velocity group, the first two shots went into the same hole. Shot three landed more than an inch away, and shot four went into the hole formed by shots one and two. If I were shooting groups containing fewer shots, I might have been tempted to take that three-shot cloverleaf (which measured 0.241″) as a group–calling the other shot a “flier.” With 10 shots, there’s no such opportunity.

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44 thoughts on “Velocity vs. accuracy: Does it REALLY matter? Part 3”

BB: I was told once (From an old airgunner) that Accupell pellets were the best all-around pellet. I believe Grosman made them but they are no longer for sale in the USA. Have you ever used them and, if so, were they that good?

Hey BB,I can't believe that you continue to churn out these blogs day after day!I know some are recycled, but still you are doing a tremendous amount of work here, not to mention the TV show, Shotgun News articles, and other stuff you are involved in.

Thanks for the good articles. Hopefully you will be able to shoot with us somewhere this fall,

I see why you picked the Whiscombe now.. Wow, what a tight spread!Your test bed seems as good as a springer could get..now on to a PCP as you suggest..Do you think, as Jane suggests, that if one keeps the pellet above the sound barrier for the full path to the target, that: not coming back through the sound barrier would help accuracy?

Suggesting a gun in the 1,100fps area and a 40 yard test, (if that would stay above the SB), might actually work better.

I still don't understand why the Evanix Blizzard does so well, giving up 1"-1-1/2" 10 shot groups at 50 yards in that 1,100 fps range.. I would set up the crony at 50 yards, and see how fast it's still going at point of impact… but I sold her, so I could buy more Marauders and have some field target stocks made for them..

Glad to hear my pistol shooting hold is safe.. with under .44 mag pistols… I sure feel comfortable with it.. and I'd hate to learn another!.. especially with the cost of ammo!

You hinted about lubed pellets.. saving the details for another article?:)

Anyway, there's a website that lists velocity vs. distance for a variety of the rifles they sell. According to their numbers, a CPL launched at around 1100fps sheds over 100fps within 10 yards… so it's probably a fair bet to say that in your tests here the pellet is subsonic by the time it gets to 15-20 yards out. But by then, of course, the damage is done – if the pellet is deviated from its path early in its flight the 'error' will only get worse the further it goes, even if the disrupting influence is removed.

Side note – I tend to use Premier Hollow Points in for most of my shooting, especially at longer ranges. Never found a pellet that's as good for the price at 60 yards, but I was always bothered by what should be the poorer aerodynamics of the HP design.

I shoot at scrap paper with targets printed on them – so I don't get nice, clean holes. The paper frequently tears, which means that I can often fold back the torn paper and look at the lead smudge where the pellet hit. And one thing I've noticed – in .22 cal, anyway – is that the smudge has a little circle in the middle from the hollow point of the pellet. The circle always looks round and centered – not oblong or eliptical – which would indicate that the pellet is hitting the target straight on as it should. If it were yawing or tumbling I'd see distortions of this pattern, but I've never noted that.

So I've got even more confidence in that pellet at 60 yards than I used to. Which is a good thing – in .22 especially they seem to be the only reasonably-priced game in town.

Now, the only question remains – are the slightly-more-expensive Benjamin packaged pellets really any better than the apparently identical Crosman packaged ones?

BB,A good experiment, although you can't disprove bias. How about a PCP in a vice, an indoor range, and a remote trigger release, not to mention weighed and measured pellets:)?

One thing I've become more and more curious about is sensitivity to wind. It seems to come from both the barrel and the projectile. I can see how the BC of the pellet affects how much wind can divert it, but I'm really confused how barrels of equal twist throwing the same projectiles can vary in "wind response", although I honestly think its happened to me and others. Do you think this really happens and why would it? By the way, I realize this is only tangentially related to the topic, but it just came to mind via association:).

I've not done a test per se on hollow point crosman vs Benjamin.. but they seem to perform the same for me.. I can't tell any difference between the two.And I don't see any major difference in the hollow point vs dome head either.. must be the partial dome of the hollow points on the crosman.. because hp on RWS are poopy for me.. same with the crow magnums.. It's just the crosman that seem to work either way.. and I didn't like the black fingers, so I didn't use them.But now with a wash with rubbing alcohol and coating with coconut oil, they are clean to hold… and shoot even better!

I think this test you did over 9 years ago proves what you suspected (bias) since "The largest low-velocity group (1.741") is still smaller than the smallest high-velocity group (2.254")–more than a half-inch smaller, in fact."

I surprised the disparity in the groups isn't larger. I've trusted your opinion about shooting pellets transonic and have selected pellets to stay around 900-950 fps at the muzzle.

In no way am I suggesting another test but can't help thinking that the best "base line" at low velocity needs to be established prior to removing the transfer port restrictor and shooting transonic. Removing as many variables should be the goal to establish the best base line.

Removing variables by weighing and sorting the most accurate pellet at 50 yards in your JW 75, adjusting the HOTS for accuracy, using at least a 20? power scope, shooting indoors, etc.

I've been shooting a lot lately at 100 yards and now that I've determined the most accurate pellet the most significant variables are wind, my shortcomings, wind, my shortcomings and scope power. My group sizes are significantly different at 7X vs. 21X at 100 yards.

I'm curious as to what power scope was used in your testing.

James Brinkley owns at least one Whiscombe JW 75 and recently launched a website dedicated to Whiscombes. He took his JW 75 out and shot at 50 yards and 100 yards with crosman premiers and beeman fts. He was adjusting his hots while doing so:

OT: Well, today I ordered the Walther PS55 red dot site from Pyramid for my Nightstalker.I feel however that it's sole purpose is going to be to make the gun look 'cooler'. Yesterday we were out shooting and could easily hit a pop can at 20 yards on a repeated basis with the stock Mohawk sights.I was out shooting with a friend who is somewhat of a local IPSC master. He figures that air guns are still somewhat for kids so he challenged me to a shoot out at 25 yards, he using his 9mmCZ and I the Nightstalker using a 25yd rapid fire pistol target.Now this test of course tells nothing…but boy was he surpised when his 10 shots were all well within the black…but mine were all in fairly tight 5" circle, centred on the target.It seems like the pellets that come out of thing are magnetically pulled to whatever I am aiming at.CowboyStar Dad

This is quite a tour de force of experimental discipline and thoroughness. I understand that Johannnes Kepler arrived at his astronomical theories by sticking rigorously to his data and ignoring his preconceptions like this.

My impressions are that I'm a little surprised that the difference between groups was not a little larger. Also, I expected a little better from the Whiscombe at 50 yards. If a 5 shot group on average is .7 of a 10 shot group and your TX200 goes under an inch at 50 yards….

Thanks for the tip on resting–a perfect geometric solution. I see the resemblance with Elmer Keith's method of resting on the knees. It also appears that most people at my range are doing it wrong.

Thanks too for the reloading info. Kevin, right you are that the advice I saw had to do with reloading surplus, and I don't plan to do that. Full steam ahead.

BG_Farmer, that's an interesting question about different wind sensitivity of identical bullets from the same twist rate. My only idea is that maybe twist rate is not such a big influence with airgun pellets. Given the heavy drag from their skirt, maybe wind quickly introduces chaotic effects that cannot be predicted sort of like the butterfly waving his wings in China creating a thunderstorm over Florida. That would make things grim for adapting David Tubb highpower wind shooting techniques to long-range airgunning.

BB,Couple of thoughts … wind coming from the left … first two shots are right on vertical … most other shots are right of target … coincidence?

Have you heard of telltales? They are long strips of cloth connected near the top of a sailboat mast to indicate wind direction. Do you or could you use something like that near your targets to judge wind direction and speed prior to pulling the trigger? Wouldn't want it connected directly to the target because it could cause it to shake more. Something like that could really minimize the wind effect by pulling the trigger only when the telltales AT THE TARGET are at the same orientation.

I wish it were that clear! I have just finished testing another PCP that grouped close to 1/2" for five shots at 50 yards when the pellets were going 1092 f.p.s. and 1088 f.p.s., on average. So what does that say about these results?

We just don't know everything there is to know yet. I do think that 10-shot groups are better predictors of accuracy than 5-shot groups.

CSD, I'd love to get Nightstalkers for my grandkids based on what you are experiencing and I think they look cool but I think they'd cost me a fortune in CO2 rapid fire. I would need a governor of some kind on each kid to slow them down but that ain't gonna happen. Maybe a rationing plan would work. Each one gets 1 88g cart and when that's gone shooting is over. Or should it be one tin? Am I reading you right – one cart per tin and one tin per cart?

Sounds like you have defied the law of physics and found something to attract lead.

Matt,Wind sensitivity does seem to affect .22LR, where the twist rate is generally considered fairly critical, but that's in the same region of velocities as BB's blog is discussing. C/F is a whole other ballgame (almost never close to transonic at any practical distance). As for pellets, like someone (Vince?) already pointed out, they have such poor BC's that velocity retention is pitiful, so unless you're shooting at very close range, they will go through a transonic "danger region" no matter how fast the initial MV.

Oh yeah, first BP rifle of my own, although I've shot several and always wanted one. Once you get past forty, you have to start getting stuff off the list:). I'm more into the history side of it, as opposed to wanting a modern inliner just to shoot deer during an extended season, but I didn't want to go crazy with it until I develop some skills.

chuck…yeah, the Nightstalker is deceiving. Only $100 bucks!!I think Crosman is doing the same thing printer manufacturers are doing…they give you a great photo-quality printer for cheap, knowing that you're going to spend a fortune on supplies!But, whoo-eee, is it fun.Since I've had it (all of 10 days), we've gone through $30 worth of CO2 and nearly $20 dollars worth of pellets.But in my opinion, it's been worth every penny.

DB, I find the trigger to be very good…to the point that I consider it a bit of a danger in the hands of someone inexperienced.It is very light, only my Slavia (which I would say has the proverbial hair trigger) is lighter. It is smooth and with no roughness that I can detect.The problem is that once the CO@ is inserted and the gun cocked…it cannot be de-cocked. So the gun is always cocked and ready to go. Before given to my 8 year old to try he got a very stern lecture on the importance of engaging the safety WHENEVER he wasn't actually shooting.CowBoyStar Dad

All,Thinking about the 30 or so shots taken last week with my modified Daisy 953 and the pellets were spiraling. Could see it through the scope and POI moved with distance to target.

So since it is raining and can not shoot or work; popped off the muzzle break to check the crown. Lots of rust on the end of the barrel and the crown was square and not beveled. It was machined with a small (may 1/64”) counter sink but flat and not beveled.

I’m used to Crosman guns and they always have a beveled crown. Is this normal for a 953?

DB,Thanks for the 1077 advice. I already have one of those but, like CSD, the looks of the Nightstalker is what attracts me and I would think the kids would think so, too. My 1077 is not very accurate, however. I have not found a pellet that it likes, yet. I am wondering about the Nightstalker in that regard, however, it sounds like CSD is getting pretty accurate results with his.

Right now I have a Marauder on order so any other purchases will have to wait for a while. And, I still have to get a scuba tank.

I've been doing research on private parties purchasing guns here in NJ. I know, in addition to Vince, there are two others who live in Jersey. So here's what I found: Title 2C:58-3 states you can buy rifles or shotguns provided you have the NJ Firearms ID card and you fill out the Certification of Eligibility, a one page form that doesn't get filed ANYWHERE. You and the seller just have to hold on to them. I have the website if anyone's interested in the form.

Now for a handgun, that purchase can only be done via a licensed retailer. Of course, technically you need the instant check for either a long arm or a handgun but that is NOT in NJ law and since the Federal Gov't and the ATF do not consider pellet rifles or handguns as firearms, no instant check.

So I've put an ad in the local pennysaver and will let everyone know what the results are. You also are supposed to put in the ad that the buyer (me) must have a valid ID card, which I did (misdemeanor if you don't state that in the ad).

Bottom line, if after next week, you don't hear from me for 6 months, I've probably been arrested and serving time :). Boy, would that be embarrassing.

DB,There's lots of stuff online about crowning barrels, but I would be certain there's something wrong with the original before trying anything. The countersink may not look impressive, but as long as it exposes the rifling evenly and is concentric, it should work fine in a low powered pellet rifle. I would try cleaning the barrel and crown first, then if you still think the crown needs it, try one of the techniques involving a round tool and mild compound. You can screw up a barrel fast when you mess up the crown, so make sure it needs it first.

Fred,The kids go off to college, and you go to the big house — not the usual empty-nest routine:).

DBI've read on other forums that upping thefps can hurt the accuracy on some 953's.May have something to do with twistrates ?Before messing with the square cutcrown on it I would try cleaning the bbland try heavier pellets to bring the fpsback down.If that and other suggestions you may get don't work then try crowning.I can't say how many fps I got from the mod cause I don't have a chrony but itdidn't seem to affect accuracy at all.I can still get dime size or smaller 10 shot groups at 30 ft.and reliably hitbottle tops out to 90 ft.with onlyslight holdover or under.That's aboutthe limit of my plinkin abilities good luck with it.

JTinAL,Good shoot'n. I've only put about 50 shots through it since the mods.

Yes heavier pellets were a bit more accurate. But they were also more accurate before the mods. At 15-yards dime size is possible. At 25-yards you can watch the pellets spiral… they fly pretty slow still.

Prior to the mod shooting at 25-yards was really difficult. It was just too weak. With the mod it is still shooting way below the factory stated speed. Doubt it is shooting too fast for the rifling; though it could be possible.

My attempts to get it to shoot well at various ranges is to make it functional for its future owner… a 7-year old boy. Though I doubt he will be shooting much past 15-yards and mostly at closer range… I want to make it as nice as possible.

In my Steyr LG100ZM, I was using the original JSB Exact Heavy pellets. For those pellets, I found that if I kept my speeds below about 890fps, I would get single-hole accuracy at 30yds. If I increased the speed to about 910fps, I would get about 1.5" "groups." I have never seen another pellet that is as speed-sensitive (and JSB no longer makes that model pellet — the current ones are not nearly as speed-sensitive).

Fred, I always understood the same thing. When I bought a Red Ryder in DE last year for my lil' girl, Dick's sporting goods needed my FID and I had to fill out a certificated of eligibility. But beyond that, no problem at all.

If Pyramydair did the same thing, it seems to me that they'd be in full compliance with NJ law…

You do a lot of interesting testing. Good tests always end with you opening the door for yet more questions!

Agreed, the test should be tried with a PCP. It is not clear if the additional group size is due to the pellet flight, or to the different recoil of the springer – or some combination of the two.

QUESTION: Did you change the sights between the groups? If not it seems that the higher velocity shots are below and to the left of the slower shots, which seems odd to be just a variation due to pellet velocity.

I'd believe results from a PCP to be more representative of the pellet flight itself.